This invention relates in general to television receiver power supplies and in particular to an efficient power supply for a television receiver that requires a small amount of standby power when in the off condition.
Modern television receivers are both microprocessor controlled and remotely controllable and require a low level of standby power when the television receiver is off to maintain the microprocessor and remote control functions. Such receivers generally include a very efficient switched mode power supply which has the undesirable characteristic of being inefficient when supplying low levels of power. The standby power requirement of a typical television receiver is on the order of a couple of watts whereas its normal operating power requirement may be on the order of one hundred watts. Because of the switched mode power supply's inefficiency at low power levels, as much as 10 to 12 watts may be consumed in the standby or off mode of the television receiver in order to supply its small standby power needs. The bulk of the power is dissipated as losses in the switched mode power supply. A few television receivers incorporate a separate standby power supply for supplying the minimal standby power requirements of the television receiver and simply turn off the switched mode power supply when the television receiver is turned off. That is a relatively expensive solution to the problem and the invention solves the problem in a much more practical manner.